.middle {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.middle > div:nth-child(1) {
    flex-direction: column;
/ / column：主轴为垂直方向，起点在容器的上沿。 display: flex;
    justify-content: center;
    height: 130px;
    width: 900px;
}

.middle > div:nth-child(1) > div {
    display: flex;
    justify-content: center;
}

.middle > div:nth-child(1) > div:nth-child(1) > div:nth-child(1) {
    background-color: aquamarine;
    border: 2px solid rgb(218, 25, 80);
    margin-top: 30px;
    margin-bottom: 30px;
}

.middle > div:nth-child(1) > div:nth-child(1) > div > div:nth-child(1) {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 30px;
}

.middle > div:nth-child(1) > div:nth-child(1) > div > div:nth-child(2) {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
}

.middle > div:nth-child(2) {
    height: 1000px;
    width: 1200px;
    background-image: url("../img/bg3.jpg");
    background-size: 100% 100%;
}

.middle > div:nth-child(2) > div:nth-child(1) > div {

    font-size: 30px;
    width: 120px;
    margin-left: 70px;
    border-bottom: 4px solid red;
}

/*--------------------------第一栏-----------------------------------*/
.middle > div:nth-child(2) > div:nth-child(2) {
    display: flex;
    flex-direction: row;
    justify-content: center;
    margin-top: 20px;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(1) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(1) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(1) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(1) > div:nth-child(3) {
    text-indent: 2em;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 120px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(3) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(3) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(3) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(3) > div:nth-child(3) {
    text-indent: 2em;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(4) {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 120px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(5) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(5) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(5) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(2) > div:nth-child(5) > div:nth-child(3) {
    text-indent: 2em;
    color: white;
}

/*------------------------箭头----------------------------------------*/
.middle > div:nth-child(2) > div:nth-child(3) {
    display: flex;
    justify-content: center;
}

.middle > div:nth-child(2) > div:nth-child(3) > div {
    display: flex;
    flex-direction: row-reverse;
    width: 840px;
    height: 100px;
    /*border: 2px solid rgb(218, 25, 80);*/
    /*transform: rotate(90deg);*/
}

.middle > div:nth-child(2) > div:nth-child(3) > div > div {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100px;
    width: 100px;
    /*border: 2px solid rgb(218, 25, 80);*/
    transform: rotate(90deg);
}

/*--------------------------第二栏-----------------------------------*/
.middle > div:nth-child(2) > div:nth-child(4) {
    display: flex;
    flex-direction: row;
    justify-content: center;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(1) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(1) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(1) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 120px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    transform: rotate(180deg);
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(3) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(3) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(3) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(3) > div:nth-child(3) {
    text-indent: 2em;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(4) {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 120px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    transform: rotate(180deg);
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(5) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(5) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(5) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(4) > div:nth-child(5) > div:nth-child(3) {
    text-indent: 2em;
    color: white;
}

/*------------------------箭头----------------------------------------*/
.middle > div:nth-child(2) > div:nth-child(5) {
    display: flex;
    justify-content: center;
}

.middle > div:nth-child(2) > div:nth-child(5) > div {
    display: flex;
    flex-direction: row;
    width: 840px;
    height: 100px;
    /*border: 2px solid rgb(218, 25, 80);*/
    /*transform: rotate(90deg);*/
}

.middle > div:nth-child(2) > div:nth-child(5) > div > div {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100px;
    width: 100px;
    /*border: 2px solid rgb(218, 25, 80);*/
    transform: rotate(90deg);
}

/*--------------------------第三栏-----------------------------------*/
.middle > div:nth-child(2) > div:nth-child(6) {
    display: flex;
    justify-content: center;
}

.middle > div:nth-child(2) > div:nth-child(6) > div {
    display: flex;
    flex-direction: row;
    /*border: 2px solid rgb(218, 25, 80);*/
    width: 850px;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(1) {
    width: 200px;
    height: 240px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(1) > div:nth-child(1) {
    display: flex;
    justify-content: center;
    background-color: black;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(1) > div:nth-child(2) {
    display: flex;
    justify-content: center;
    background-color: black;
    font-size: 20px;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(2) {
    width: 500px;
    height: 240px;
    margin-left: 30px;
    /*border: 2px solid rgb(218, 25, 80);*/
    background-color: red;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(2) > div:nth-child(1) {
    margin-top: 30px;
    font-size: 25px;
    width: 100px;
    height: 50px;
    margin-left: 70px;
    border-bottom: 4px solid black;
    color: white;
}

.middle > div:nth-child(2) > div:nth-child(6) > div > div:nth-child(2) > div:nth-child(2) {
    margin-top: 30px;
    font-size: 20px;
    text-indent: 2em;
    color: white;
}